Preheat oven to 350 degrees. Grease and line a 9 x 5 inch loaf pan with parchment paper.
Add 2-3 large bananas to a bowl and mash with an electric mixer. Measure 1 cup of mashed bananas and set aside.
Cream softened, unsalted butter and granulated sugar together in a large bowl with an electric mixer.
Then add in eggs and vanilla and combine.
Next add in the mashed bananas and mix.
Then mix in the buttermilk.
In a small bowl whisk together the all purpose flour, cocoa powder, baking soda and salt.
Add the dry ingredients to the wet ingredients and combine.
Lastly mix in the semisweet chocolate chips.
Pour batter into prepared pan. Bake the banana bread for 70 - 75 minutes, or until a toothpick/cake tester comes out clean from the center.
Let the banana bread cool in the pan for 20 minutes and then transfer to a cooling rack to completely cool. Sprinkle extra chocolate chips on top after baking for looks if you desire.
Store left overs in an airtight container for up to 4 days. Refrigerate after day two.